It has been challenging to simultaneously improve photosynthesis and stress tolerance in plants. Crassulacean acid metabolism (CAM) is a CO₂-concentrating mechanism that facilitates plant adaptation to water-limited environments. We hypothesized that the ectopic expression of a CAM-specific phosphoenolpyruvate carboxylase (PEPC), an enzyme that catalyzes primary CO₂ fixation in CAM plants, would enhance both photosynthesis and abiotic stress tolerance. To test this hypothesis, we engineered a CAM-specific PEPC gene (named AaPEPC1) from Agave americana into tobacco. In comparison with wild-type and empty vector controls, transgenic tobacco plants constitutively expressing AaPEPC1 showed a higher photosynthetic rate and biomass production under normal conditions, along with significant carbon metabolism changes in malate accumulation, the carbon isotope ratio δ¹³C, and the expression of multiple orthologs of CAM-related genes. Furthermore, AaPEPC1 overexpression enhanced proline biosynthesis, and improved salt and drought tolerance in the transgenic plants. Under salt and drought stress conditions, the dry weight of transgenic tobacco plants overexpressing AaPEPC1 was increased by up to 81.8% and 37.2%, respectively, in comparison with wild-type plants. Our findings open a new door to the simultaneous improvement of photosynthesis and stress tolerance in plants.

The exceptional physicochemical properties of selenium nanoparticles (SeNPs) have led to their widespread development. The function of SeNPs is significantly influenced by their shape and particle size, which are in turn determined by the applied synthesis methods. This work presents a critical and comparative analysis of physical, chemical, and biosynthetic methods. The key point is to elaborate on how different methods precisely regulate the particle size, morphology, and stability that are crucial to their functional efficacy. This work emphasizes the importance of creating standardized protocols for characterizing SeNPs in order to make meaningful comparisons between the effectiveness of various studies. We further elucidate the underlying mechanisms of SeNPs’ anti-tumor, antioxidant, and antibacterial activities. A key novelty of this work lies in its systematic construction of a bridge between the synthesis, properties, functions, applications, and translational potential and its provision of a critical assessment. Finally, the review identifies and summarizes the principal challenges hindering clinical and commercial translation, including the imperative for standardized toxicological evaluation, scalable synthesis, and regulatory alignment.

Heat shock proteins (HSPs) play various stress-protective roles in plants. In this study, three HSP genes were isolated from a suppression subtractive hybridization (SSH) cDNA library of Ginkgo biloba leaves treated with cold stress. Based on the molecular weight, the three genes were designated GbHSP16.8, GbHSP17 and GbHSP70. The full length of the three genes were predicted to encode three polypeptide chains containing 149 amino acids (Aa), 152 Aa, and 657 Aa, and their corresponding molecular weights were predicted as follows: 16.67 kDa, 17.39 kDa, and 71.81 kDa respectively. The three genes exhibited distinctive expression patterns in different organs or development stages. GbHSP16.8 and GbHSP70 showed high expression levels in leaves and a low level in gynoecia, GbHSP17 showed a higher transcription in stamens and lower level in fruit. This result indicates that GbHSP16.8 and GbHSP70 may play important roles in Ginkgo leaf development and photosynthesis, and GbHSP17 may play a positive role in pollen maturation. All three GbHSPs were up-regulated under cold stress, whereas extreme heat stress only caused up-regulation of GbHSP70, UV-B treatment resulted in up-regulation of GbHSP16.8 and GbHSP17, wounding treatment resulted in up-regulation of GbHSP16.8 and GbHSP70, and abscisic acid (ABA) treatment caused up-regulation of GbHSP70 primarily.

Premna microphylla is widely used in the Chinese folk medicine for the treatment of different infections diseases. In this study, ascorbic acid and β-carotene contents of the fresh P. microphylla leaves and stems were determined byspectrophotometric method. In addition, the antioxidant and antibacterial activities and phenolic contents of the methanol extracts of the dry leaves and stems were evaluated using in vitro standard methods. The results showed that ascorbic acid and β-carotene contents of the leaves and stems were both considerable. The antioxidant activities of the stem extract of P. microphylla as determined by the total phenolics, flavonoids, and ferrous reducing antioxidant property methods were significantly higher than that of leaves. On the other hand, the leaf extract of the plant had higher level of proanthocyanidins. Moreover, the leaf extract also had higher radical scavenging activity than the stem as shown in 1,1-Diphenyl-2-picrylhydrazyl assay. The antibacterial assay showed that the methanol extracts from the leaves and stems had significant activity against both Gram-positive and Gram-negative bacteria. The activity of the leaf extract was more pronounced on several bacterial species, compared with that of stem extract on three bacterial species with the minimum inhibitory concentrations of 10 mg/ml. The results obtained in this study suggested P. microphylla could be a potential good candidate for functional foods as well as pharmaceutical plant-based products. Key words: Premna microphylla, antioxidant, antibacterial, methanol extract.

As one of the rare and precious wood species since the ancient times, Gingko is also known as “living fossil”, which is a special plant resource of China. Gingko leaves, containing rich flavonoids, are valued with great medicinal significances. This paper treated Ginkgo seedlings by exogenous Sodium selenite (SS) in two ways: Foliage dressing (FD) and Root application (RA). Then transcriptome sequencing and metabolome test are performed. Results show that external SS has significant influence on the related gene expression level of flavonoids synthesis ways of Gingko, the FD can significantly induce gene expressions as CHS, FLS, FOMT, PAL, MYB1 and MYB2, and RA can significantly induce gene expressions as FOMT, MYB1 and MYB2. Compared with the control group, FA selenium application can help to accumulation of flavonoids, flavonols, flavonoids-C and isoflavones, especially quercetin and kaempferol that had a remarkable increase. This proved that a proper concentration of inorganic SS could promote the synthesis and accumulation of flavonoids in Gingko. qRT-PCR analysis also depicts that leaves treatment of sodium selenite can remarkably enhance the gene expression of CHS, FLS, FOMT and PAL, and RA selenium application can induce the gene expression of FLS and FOMT, but restrain the gene expression of CHS and PAL. Through the ways of FD and RA selenium application, this paper basically studied the regulatory effect of SS on ginkgo flavonoids synthesis and has laid a theoretical basis to improve flavonoids content in Ginkgo leaves through cultivation control means. ********* In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 3, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue. *********